Performance, Brainstorming & TuningTalk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

First off, I want to use a two-piece A/C Compressor mount instead of the one piece mount that wraps around the edge of the block and attaches to the motor mount pads. To do this, I need to take an inch off the spacer for the torque axis mount (it uses the same block mounting hole as the A/C bracket.)

Here'* the cut-off tool on the lathe cutting off the extra inch.

And here'* the spacer back in place with the A/C mount sandwiched between it and the block.

Next, I need to do something with the fuel rails. My 1990 Bonneville does not have the quick disconnect fittings (they came to GM-Land a few years later) so I need a standard pipe fitting of some sort on the rail. I decided to go with AN pipe fittings (-6 for the feed line, -4 for the return to the tank.) These are pretty standard hot-rod stuff, but to fit them on the rails, I had to machine custom ones. For the feed line, I took a male AN-6 to male AN-6 fitting, bored one end out to 3/8", then machined the threads off on one side. The finished fitting was then silver soldered onto the injector rail pipe. The return is the same, only using a -4 fitting bored out with a 1/4" hole.

And last, but not least, a custom plug for the EGR port on the intake manifold

No. The gaskets that need trimmed are the end of the block, not the intake-to-head gaskets.

Personally, I don't know if the latest and greatest aluminum frame gaskets work any better than the plastic framed ones. They are all putting a lot of faith in a thin little rubber bead around the head coolant passages.

It will be interesting to see how your RTV around the coolant ports holds up. Of course, only the long term will tell.

Yeah, Me too. It'* a gamble of sorts, but I'm betting I know why they leak in the first place and the extra wide bead of RTV around the coolant passages should solve it.

After a long week on the job, and a few trips to the auto parts store. I can finally mock up the accessory drive belts.

The arrangement I came up with is a "bastard" drive system. The Supercharger belt is using the 1997 Bonneville arrangement with a Goodyear 4060725 belt, 3.5" tensioner pulley, and 3" idler. The Accessory drive is 2000 Grand Prix, using a Goodyear 4060915 belt and 3" tensioner pulley. As you can see, the belt arrangement works and I can use the late model alternator, with the 1997 Torque Axis motor mount.

Another little factoid...I used the pressed steel pulleys whenever possible instead of the plastic ones. The reason is pretty simple...the bearings are usually what goes bad on an idler. Those bearings are sealed roller bearings with common sizes and are readily available. Here on the east coast of Florida there'* an outfit called "Miller Bearings" that stocks most of the metric bearings and they are far cheaper than new idler & tensioner pulleys. With a steel pulley, use an appropriate socket that fits the outer race of the bearing and drive the bearing out of the center of pulley. Then plop that bearing down on the counter and you can get a replacement for about $2. (The inner, outer, and width dimensions in milimeters is stamped into the side of the bearing) Then drive the new bearing into the steel pulley, check that it'* seated square, and you are good to go. Beats blowing $30 on a replacement pulley. This only works on the steel pulleys. The plastic ones are cast around the bearing, locking it in place.

Now, with any luck at all, the two plastic coolant elbows and water neck will be in tomorrow. With that I can finish the front of the motor for real and pressure test the coolant passages for leaks. I still need to take the motor off the engine stand tomorrow and install the rear cover and crank seal to finish up the assembly (just not enough room to do this on the engine stand). Everything else will wait until the motor is installed in the car.

RE: the pulleys. I have never had a long lasting aftermarket pulley. The aftermarkets I used for a few years were Factory Air brand. I could get about 10k miles outta them. Finally just started carrying a spare in the trunk in case I had to change one out roadside. (high usage service vehicle) A trip to the junkyard a few years ago netted me some used OEM ones that are still running.

Did you use the Factory Air brand or a better one?

Nice factiod about changing just the bearings. I think I may still have some of the stamped idlers lying around somewhere

The two 3" idlers are original GM with new Timken roller bearings. The 3.5" smooth idler is a Dayco replacement, and the ribbed idler on the SC belt is a GM replacement plastic (PN 125645509)

The bearing trick came to me via a motorcycle buddy. For years I bought bearings for the bikes at the Honda dealer, at a rediculous markup. Then said buddy slapped me upside the head and explained the standard markings on the sides of the bearings. From that point on I've bought the bearings and seals from Miller.

Oh, I also picked up the thermostat today (Stant 13848, 44mm 180 degree) which I need to drill for relief holes and install tomorrow as well.

No dice on the coolant elbows and water-neck, so I figured I could test a few of the sub-systems to see that everthing was working as it should prior to being installed in the car.

This little "Rube Goldberg" contraption is how I test the injector rails and the injectors themselves. In the photo, the gauges are regular R-12 A/C manifold gauges. Since I converted the rail to run with AN-4 fittings on the outlet side, no adaptors were needed to hook these up. The red hose (High Pressure gauge) is connected to the schraeder valve on the opposite side of the motor. The blue hose (Low Pressure gauge) is connected to the fuel return line. The black hose is from the air compressor in the garage and is connected via a coupling (quick disconnect barb to 3/8 NPT, then to a 3/8 NPT to AN-6 fitting) to the AN-6 fitting I installed on inlet side of the rail. The little hand pump is connected to the vac fitting on the fuel pressure regulator.

If your rails are regular GM quick disconnects, you can do the same thing but you will need to buy or make converters (using a junkyard pair of GM fuel lines and hose barbs)

With the rail pressurized, I'm listening for any hissing air that would indicate a stuck injector or an O-ring failure. As you bring the air pressure up, you low side gauge will suddenly jump from 0 to the high side pressure. That'* the point where the regulator is opening to dump the excess pressure overboard. Try it a couple of time with various amounts of vac and pressure on the regulator fitting and you can map out actual fuel rail pressure the regulator will set vs. the amount of boost or vac signal comming from the manifold. (Crack open the low side of the A/C Manifold gauges so the output of the regulator has some place to go...it can only dump the excess pressure to the return line, so you have to open the return line and allow the pressure drop to occur)

For reference sake, I plotted the rail pressure vs. the signal vac. With zero signal pressure, the regulator opens at 54 psi rail pressure. With 20 inches of vac on the regulator signal, the regulator opens at 50 psi rail pressure. The regulator is linear, with about a 1 psi drop in rail pressure for every 5 inches of vac. I ran out of pressure gauges, so I can't measure the rail pressure vs. positive boost pressure on the regulator, but I would venture a guess that it will also be linear.

With a battery, pushbutton, and an old chunk of injector wiring harness, I can go down the line and pulse each injector, listening for an audible hiss of air when the injector open.

With this rig, you can also clean out the injectors off the car. Fill the rail and injectors up with carb cleaner. Let it sit for a little while to give the cleaner a chance to dissolve the varnish inside, then hook up the air pressure and start pulsing the injectors. If you do it on the work bench, you can stick the end of the injector in a can to catch the cleaner comming out when you pulse the injector. You can also see the spray pattern from the injector. Not really great for checking the actual flow rates, but good enough to know the injectors are going to work and you aren't going to be dumping fuel all over the place as soon as the pump kicks in.

Time to take the motor off the stand and get the rear cover on. Like the intake manifold, I'm not relying solely on the paper gasket. I've cleaned the gasket surface on the block with acetone and applied a small bead of RTV around the coolant openings in the rear of the block. And a little more around the cover seams down to the oil pan.

Gasket and cover go on next, along with the rear seal installed in the cover. This was an assembly mistake. I drove the seal on from the front side of the cover, flush with the face of the cover. After install I realized the seal was too far out and needs to be flush on the inside of the cover in order to seal the crank properly. At this point, the only thing to do was to carefully drive it in a little further and as square as I can make it. (I might need to pull it later and make a proper press to put a new one in if this one leaks.)

Flexplate back on and ready to go back on the engine stand. I need to get some flexplate bolts as they are also torque to yield. I may opt to get some regular flexplate bolts and torque them the old way. That will be Ok, I still have a few weeks left before the motor goes in the car.

With that, the basic motor is complete. All that is left to do is mount the throttle body, starter, and wait for the injectors to come back from being cleaned. Then she'll be ready to install in the car.